diff --git a/compiler/rustc_infer/src/traits/mod.rs b/compiler/rustc_infer/src/traits/mod.rs
index 7e7c8588ffb40..a3c4920fa8af3 100644
--- a/compiler/rustc_infer/src/traits/mod.rs
+++ b/compiler/rustc_infer/src/traits/mod.rs
@@ -57,7 +57,7 @@ pub type TraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>;
 
 // `PredicateObligation` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(target_arch = "x86_64")]
-static_assert_size!(PredicateObligation<'_>, 40);
+static_assert_size!(PredicateObligation<'_>, 32);
 
 pub type Obligations<'tcx, O> = Vec<Obligation<'tcx, O>>;
 pub type PredicateObligations<'tcx> = Vec<PredicateObligation<'tcx>>;
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index d6cf68a900ce0..b7530c077ccd1 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1751,9 +1751,6 @@ pub struct ParamEnv<'tcx> {
     ///
     /// Note: This is packed, use the reveal() method to access it.
     packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, traits::Reveal, true>,
-
-    /// FIXME: This field is not used, but removing it causes a performance degradation. See #76913.
-    unused_field: Option<DefId>,
 }
 
 unsafe impl rustc_data_structures::tagged_ptr::Tag for traits::Reveal {
@@ -1834,7 +1831,7 @@ impl<'tcx> ParamEnv<'tcx> {
     /// Construct a trait environment with the given set of predicates.
     #[inline]
     pub fn new(caller_bounds: &'tcx List<Predicate<'tcx>>, reveal: Reveal) -> Self {
-        ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, reveal), unused_field: None }
+        ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, reveal) }
     }
 
     pub fn with_user_facing(mut self) -> Self {
diff --git a/compiler/rustc_mir_build/src/thir/pattern/_match.rs b/compiler/rustc_mir_build/src/thir/pattern/_match.rs
index 904524e13ae08..04de9a7a58dda 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/_match.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/_match.rs
@@ -1787,9 +1787,32 @@ impl<'tcx> IntRange<'tcx> {
         param_env: ty::ParamEnv<'tcx>,
         pat: &Pat<'tcx>,
     ) -> Option<IntRange<'tcx>> {
-        match pat_constructor(tcx, param_env, pat)? {
-            IntRange(range) => Some(range),
-            _ => None,
+        // This MUST be kept in sync with `pat_constructor`.
+        match *pat.kind {
+            PatKind::AscribeUserType { .. } => bug!(), // Handled by `expand_pattern`
+            PatKind::Or { .. } => bug!("Or-pattern should have been expanded earlier on."),
+
+            PatKind::Binding { .. }
+            | PatKind::Wild
+            | PatKind::Leaf { .. }
+            | PatKind::Deref { .. }
+            | PatKind::Variant { .. }
+            | PatKind::Array { .. }
+            | PatKind::Slice { .. } => None,
+
+            PatKind::Constant { value } => Self::from_const(tcx, param_env, value, pat.span),
+
+            PatKind::Range(PatRange { lo, hi, end }) => {
+                let ty = lo.ty;
+                Self::from_range(
+                    tcx,
+                    lo.eval_bits(tcx, param_env, lo.ty),
+                    hi.eval_bits(tcx, param_env, hi.ty),
+                    ty,
+                    &end,
+                    pat.span,
+                )
+            }
         }
     }
 
@@ -2196,6 +2219,7 @@ fn pat_constructor<'tcx>(
     param_env: ty::ParamEnv<'tcx>,
     pat: &Pat<'tcx>,
 ) -> Option<Constructor<'tcx>> {
+    // This MUST be kept in sync with `IntRange::from_pat`.
     match *pat.kind {
         PatKind::AscribeUserType { .. } => bug!(), // Handled by `expand_pattern`
         PatKind::Binding { .. } | PatKind::Wild => None,
diff --git a/compiler/rustc_trait_selection/src/traits/fulfill.rs b/compiler/rustc_trait_selection/src/traits/fulfill.rs
index 7e5be8276f7ff..fdebd88a086c7 100644
--- a/compiler/rustc_trait_selection/src/traits/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/traits/fulfill.rs
@@ -87,7 +87,7 @@ pub struct PendingPredicateObligation<'tcx> {
 
 // `PendingPredicateObligation` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(target_arch = "x86_64")]
-static_assert_size!(PendingPredicateObligation<'_>, 64);
+static_assert_size!(PendingPredicateObligation<'_>, 56);
 
 impl<'a, 'tcx> FulfillmentContext<'tcx> {
     /// Creates a new fulfillment context.